Conventionally, adsorption of small molecules is achieved using molecular sieves or zeolites contained in a packed-bed system or a honeycomb-structured system.
A packed-bed system has a high adsorption capacity. It is regenerated after the system reaches its full adsorption capacity. The regeneration, a prolonged process (e.g., 24 hours), requires a significant amount of energy. A honeycomb-structured system is less effective in adsorption than a packed-bed system, as it has a high mass transfer resistance. Further, it is large in size and expensive to operate.
A recently developed hollow-fiber adsorption system has a higher adsorption capacity and a lower mass transfer resistance than both the packed-bed system and the honey comb-structured system. Its operational cost is low as it can be regenerated rapidly at a low temperature. See Perera and Tai, International Patent Application Publication WO 2008/110820 A1; Perera, International Patent Application Publication WO 2007/007051 A1; and Tai, Novel Adsorbent Hollow Fibers, Ph.D. thesis, University of Bath, UK (2007). Due to their low mass transfer resistance, existing hollow fibers do not hold a high-speed gas or liquid long enough for effective adsorption. See Lee et al., Adsorption Science and Technology, 18, 147-70 (2000).
Hollow fibers have also been used in filtration. However, they are not suitable for filtration of a high-speed gas or liquid.
There is a need to devise a hollow fiber efficient for adsorption or filtration.